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We show that the time evolution of density operator of open qubit system can always be described in terms of the Kraus representation. A general scheme on how to construct the Kraus operators for an open qubit system is proposed, which can…

Quantum Physics · Physics 2015-06-26 D. M. Tong , Jing-Ling Chen , L. C. Kwek , C. H. Oh

We describe the representation of arbitrary density operators in terms of expectation values of simple projection operators. Two representations are presented which yield non--recursive schemes for experimentally determining the density…

Quantum Physics · Physics 2009-10-28 Ole Steuernagel , John A. Vaccaro

Of crucial importance to the development of quantum computing and information has been the construction of a quantum operations formalism that admits a description of quantum noise while simultaneously revealing the behavior of an open…

Quantum Physics · Physics 2011-05-09 Colin Wilmott

The necessity and utility of considering the interaction of a quantum system with its environment when describing its time evolution have been recognized in several branches of physics and of other sciences. The Kraus' representation is a…

Quantum Physics · Physics 2016-05-12 Jonas Maziero

We showed several years ago that the density operator of Markovian open systems can be diagonalized continuously in time. The resulting pure state jump processes correspond to quantum trajectories proposed in recent quantum optics…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Lajos Diosi

We study the reduced time-evolution of open quantum systems by combining quantum-information and statistical field theory. Inspired by prior work [EPL 102, 60001 (2013) and Phys. Rev. Lett. 111, 050402 (2013)] we establish the explicit…

Statistical Mechanics · Physics 2019-07-26 V. Reimer , M. R. Wegewijs

We propose a way to understand the evolution of an open quantum system using a description that dispenses a continuous evolution in time, by discrete operators entangled states, in its most direct and fundamental way. We show that the…

Quantum Physics · Physics 2016-02-17 Bernabé Mejía , Hernán A. Castillo

In this work, the operator-sum representation of a quantum process is extended to the probability representation of quantum mechanics. It is shown that each process admitting the operator-sum representation is assigned a kernel, convolving…

Quantum Physics · Physics 2022-02-03 Yan Przhiyalkovskiy

Based on a recent proof of free choices in linking equations to the experiments they describe, I clarify relations among some purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and…

Quantum Physics · Physics 2014-09-15 John M. Myers

In this note, we develop a framework to describe open quantum systems in the Heisenberg picture, i.e., via time evolving operator algebras. We point out the incompleteness of the previous proposals in this regard. We argue that a complete…

Quantum Physics · Physics 2020-12-01 Nachiket Karve , R. Loganayagam

Nonlinear dynamical systems are ubiquitous in science and engineering, yet analysis and prediction of these systems remains a challenge. Koopman operator theory circumvents some of these issues by considering the dynamics in the space of…

Numerical Analysis · Mathematics 2020-02-17 Mason Kamb , Eurika Kaiser , Steven L. Brunton , J. Nathan Kutz

We consider a closed quantum system subject to a stochastic resetting process. The generic expression for the resulting density operator is formulated for arbitrary resetting dynamics, fully characterised by the distribution of times…

Quantum Physics · Physics 2023-02-15 Francisco J. Sevilla , Andrea Valdés-Hernández

We introduce superdensity operators as a tool for analyzing quantum information in spacetime. Superdensity operators encode spacetime correlation functions in an operator framework, and support a natural generalization of Hilbert space…

Quantum Physics · Physics 2018-10-17 Jordan Cotler , Chao-Ming Jian , Xiao-Liang Qi , Frank Wilczek

Quantum operations are usually defined as completely positive (CP), trace preserving (TP) maps on quantum states, and can be represented by operator-sum or Kraus representations. In this paper, we calculate operator-sum representation and…

Quantum Physics · Physics 2013-04-23 Mahmoud Mahdian , Hadi Mehrabpour

We investigate completely positive maps for an open system interacting with its environment. The families of the initial states for which the reduced dynamics can be described by a completely positive map are identified within the framework…

Quantum Physics · Physics 2014-07-09 Longjiang Liu , D. M. Tong

We introduce the Gaussian quantum operator representation, using the most general multi-mode Gaussian operator basis. The representation unifies and substantially extends existing phase-space representations of density matrices for Bose…

Quantum Physics · Physics 2009-11-10 Joel F. Corney , Peter D. Drummond

In the contest of open quantum systems, we study a class of Kraus operators whose definition relies on the defining representation of the symmetric groups. We analyze the induced orbits as well as the limit set and the degenerate cases.

Mathematical Physics · Physics 2021-08-25 Alessia Cattabriga , Elisa Ercolessi , Riccardo Gozzi , Erika Meucci

In this paper, we give a multiplication operator representation of bounded self-adjoint operators T on a Hilbert space H such that -- is a frame for H, for some -- . We state a necessary condition in order for a frame -- to have a…

Functional Analysis · Mathematics 2023-01-18 Jahangir Cheshmavar , Ayyaneh Dallaki , Javad Baradaran

We consider the representation of operators in terms of tensor networks and their application to ground-state approximation and time evolution of systems with long-range interactions. We provide an explicit construction to represent an…

Quantum Physics · Physics 2010-07-20 F. Fröwis , V. Nebendahl , W. Dür

Electron transport in realistic physical and chemical systems often involves the non-trivial exchange of energy with a large environment, requiring the definition and treatment of open quantum systems. Because the time evolution of an open…

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